Background: Toxocariasis is the clinical terms applied to infection of human with Ascarid nematodes in the order Ascaridida, named Toxocara canis and T. cati. Because in recent years in Iran many people desire to keep pets (cats and dogs), and lacking of seroepidemiological study of toxocariasis in Mashhad, we decided to determine the seroprevalence of toxocariasis among people who own cats and dogs in comparison with control group.Methods: A serological study for detection antibodies to Toxocara in two groups (93 cat and dog owners and 93 healthy people as control group) was conducted from Feb 2013 to Dec 2013. An ELISA method was employed using determination of IgG antibodies against Toxocara. The serum samples were evaluated for anti- Toxocara antibody, using ELISA technique at Parasitology and Immunology Lab of Imam Reza Hospital of Mashhad. Using a questionnaire, epidemiological factors associated with infection were examined. Data were analyzed using Chi-square test.Results: The seroprevalence of Toxocara antibodies in the pet owners and control group was respectively 20.43% and 1.07%.47.3% of pet owners were female.Conclusion: Presented data showed the significant difference between seroprevalence of toxocariasis among pet owners and control group. Education of society and in particular pet owners consisting of preventing contamination of the environment with Toxocara eggs is advised.